The major and long-term objective of proposed investigation is to study the mechanism(s) of cataractogenesis and develop approaches to delay or inhibit cataract development. Cataracts induced with galactose and X-rays in rats and rabbits will be used as experimental models to fulfill our objectives. Using this model, the mechanism of cataract induction and reversal will be studied. Moreover, effect of galactose cataract inhibvitors such as flavanoids and other aldose reductase inhibitors will be investigated. Morphological techniques involving light, transmission and scanning electron microscopy and ultrastructural cytochemistry for enzyme localization will be used for all investigations. Cytochemical localization and quantitation of enzymes, such as Na-K-ATPase, catalase, peroxidases, acid phosphatase and arylsulfatase, considered to be playing an important role in galactose of X-ray induced cataractogenesis will be performed. Morphological and cytochemical investigations of normal and cataractous human lenses will also be conducted. These studies will provide useful information to understand cataractogenesis in human lenses associated with diabetes or senility.